gh-108751: Add copy.replace() function (GH-108752)

It creates a modified copy of an object by calling the object's
__replace__() method.

It is a generalization of dataclasses.replace(), named tuple's _replace()
method and replace() methods in various classes, and supports all these
stdlib classes.

Objects/codeobject.c

@@ -2145,6 +2145,7 @@ static struct PyMethodDef code_methods[] = {
     {"co_positions", (PyCFunction)code_positionsiterator, METH_NOARGS},
     CODE_REPLACE_METHODDEF
     CODE__VARNAME_FROM_OPARG_METHODDEF
+    {"__replace__", _PyCFunction_CAST(code_replace), METH_FASTCALL|METH_KEYWORDS},
     {NULL, NULL}                /* sentinel */
 };